1. Field of the Invention
The present invention is in the field of treating tumors of the central nervous system (CNS).
2. Description of the Background Art
Taurolidine (Bis-(1,1-dioxoperhydro-1,2,4-thiadiazinyl-4)methane) was developed by Geistlich Pharma. It is a white crystalline substance, water soluble up to 2%. It is made up of two molecules of taurinamid and three molecules formaldehyde forming a two-ringed structure bridged by a methylene group.
Taurolidine has primarily an antibiotic and anti-endotoxin effect. It acts by a chemical reaction, so no microorganism resistance has been observed as yet. This effect of taurolidine is mediated by its active metabolites, which are donators of active methylol-groups: Methylol-Taurultam and Methylol-Taurinamide. The active methylol groups inactivate by reacting with the cell wall of bacteria and with the primary amino groups of endotoxins.
Additional effects of taurolidine were reported in the past: inhibition of TNF and IL-1Beta in mononuclear cells (Bedrosian 1991), inhibition of Tumor Necrosis Factor Toxicity, and inhibition of Peritoneal Tumor Cell Growth in Laparoscopic Surgery (Jacobi 1997).
Taurolidine solutions have been used as instillation or rinsing solutions of the abdominal cavity in cases of peritonitis. In post-operative instillations, conscious patients have reported as a side-effect irritation of the nerves of the peritoneum, and sometimes strong burning sensations which require intravenous administration of pain killers or anaesthesia. Monson et al. PCT International Publication Number WO 92/00743 discloses a selective direct inhibiting effect of Taurolidine and/or Taurultam on certain body tumors. (Monson J R T, Ramsey P S, Donohue J H. Preliminary evidence that taurolidine is anti-neoplastic as well as anti-endotoxin and anti-microbial. Abstract. Br J Surg 77(6) 1990, A711) on B16 melanoma cells and Meth A sarcoma cells in a mice model in vivo, and on fibroblastic tumor cells, LS174T (colon-) carcinoma cells and Jurkat (leukemic-) cells in vitro (International Patent PCT No. PCT/EP91/01269, International Publication Number WO 92/00743 PCT “Use of Taurolidine and/or Taurultam for the treatment of tumors”). However, primary tumors of the brain and medulla of the Central Nervous System (CNS) are very different from those of the body. Nerve cells differ significantly from cells of other organs, and have a much more complex construction. Nerve cells are characterized by a great number of branches which serve to transmit impulses and sensations, including dendrites for reception of impulses, and neurites or axons for emission of impulses. Neurogliae are glia-cells which are present in greater numbers than neurons, and render stability to the nerve cells. Glia-cells are responsible for metabolism and protection of sensitive nerve cells. The cells from which CNS tumors arise have a different metabolism as compared to other tumor cells. Metastases of CNS tumors outside the nervous system are very rare. Effective surgical treatment is often impossible since the tumors are located in functionally important areas, or spread diffusely.
Primary tumors of the brain and spinal cord arise from the different cell types of the CNS. These cell types are neurons, which are responsible for the neuronal function and the glial cells, which have supporting and nutritioning functions. According to the different subtypes of glial and neuronal cells, there are different types of CNS-tumors. The most common brain tumors arise from the glial cells. Various sub-types (astrozytoma, oligodendroglioma, ependymoma, etc.) are encompassed by the term “glioma”.
Gliomas are the most common primary brain tumors. The incidence of gliomas is about 5/100,000 persons per year. More than 50% are glioblastoma, the most malignant form, which is responsible for more than 2.5% of the total tumor associated mortality. More than 95% of the patients die within 2 years following diagnosis despite aggressive therapy including surgery, radiotherapy and chemotherapy.
Brain tumors have some special characteristics as compared to “peripheral” tumors. They act as space occupying lesions, caused by the bony skull. This situation causes herniation and death when the tumor grows larger than can be accommodated. Furthermore, primary brain tumors often metastasize via the cerebrospinal fluid within the whole central nervous system. The brain tumor cells have a lower cohesion within the cell formation as compared to “peripheral” tumor cells (Jänisch W.: Pathologie der Geschwülste des Zentralnervensystems In: Klinische Neuropathologie, J. Cervós-Navarro and R. Ferszt (Eds.) Thieme, Stuttgart, N.Y., 1989). In addition, the metabolism of brain tumors are influenced by the blood/brain barrier.
Both types of tumors, glial and neuronal, can develop malignantly. Malignant gliomas are more frequent as compared to benign gliomas (85% vs. 15%). In the U.S. there are about 20,000 new glioma and medulloblastoma cases per year. The glioblastoma is most common (about 65% among astrocytoma).
Therapeutic options of primary CNS-tumors include surgery, radiotherapy and chemotherapy. Complete resection is often impossible because of poorly defined tumor borders and location within the brain area. Nearly all malignant glioma reoccur within months, 90% on the original site. Reoperation for a recurrent glioma typically extends survival by about 36 weeks (10 weeks with good quality of life). There is no well designed study regarding the beneficial effect of radiotherapy following glioma surgery. In patients older than 65 years, the median survival following tumor biopsy plus radiation is about 17 weeks, and following tumor removal plus radiation about 30 weeks (the peak incidence of glioblastoma is at an age of about 60 years). However, complete tumor removal plus radiotherapy is considered the reference standard in glioma therapy.
Chemotherapy using alkylating agents has a positive response rate of about 30%. A positive response generally extends the survival by 6-8 weeks. However, only about 50% of the patients treated with chemotherapy using alkylating agents are able to maintain regular activities.
Despite progress in diagnosis and treatment, the prognosis of patients with malignant primary CNS-tumors is still poor. The median survival of glioblastoma patients following optimal therapy including complete extirpation and radiation is less than about 10 months (about 1.6 years in grade III astrocytomas). The 1-year survival rate of patients with glioblastoma is about 35%, the 2-year survival rate about 8%.
Some primary malignant central nervous system tumors cannot be treated surgically because of their location or diffuse extension (gliomatosis, diffuse brain stem gliomas). Chemotherapy is not generally recommended, since the response rate on these alkylating agents (BCNU, CCNU, Procarbazine) is about 10% of patients (data from Greenberg M S. Handbook of Neurosurgery. Third edition 1994, Greenberg Graphics Inc., Lakeland, Fla., USA). Heretofore, no therapy could be offered to those patients despite a palliative radiation. Thus, the therapy of primary malignant tumors of the central nervous system has been very unsatisfactory.
There remains a need in the art for new methods and compositions for treating tumors of the central nervous system.